Development of a novel probe for measuring drug binding to the F1*S variant of human alpha 1‐acid glycoprotein

Cogswell, Lawrence P.; Raines, Douglas E.; Parekh, Sonali; Jonas, Oliver; Maggio, John E.; Strichartz, Gary R.

doi:10.1002/jps.1093

Cited by 14 publications

(22 citation statements)

References 21 publications

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“…Repeated measures of the fluorescence spectrum of a stable solution of AGP demonstrated a precision better than Ϯ2% for recordings collected over 2 to 3 h. The excitation and emission bandpasses were set at 2.5 nm and 20 nm, respectively. As previously reported (Cogswell et al, 2001), the shape of the emission spectrum of AGP was essentially independent of excitation wavelength over the range 265 to 295 nm, indicating that tyrosine residues did not contribute significantly to the observed fluorescence. Therefore, to yield the maximal fluorescence signal, the protein was excited at either 278 nm or 285 nm, near its wavelength of maximum absorbance (278 nm).…”

Section: Methodssupporting

confidence: 84%

“…Mepivacaine, were obtained from Dr. Rune Sandberg, Astra Pharmaceuticals (Sodertalje, Sweden); and bupivacaine enantiomers were obtained from CellTech Group PLC (London, UK). The probe molecule DEDIC was previously developed and synthesized in our laboratory (Cogswell et al, 2001). Water was doubly deionized to Ͼ18.2 M⍀ with a Milli-Q ultra pure water system (Millipore Corp., Bedford, MA) and was free of fluorescent contaminants.…”

Section: Methodsmentioning

confidence: 99%

“…All solutions were prepared in standard aqueous medium (SAM), containing 0.15 M NaCl and 5 mM MOPS buffer adjusted to pH 7.40. Standard practices for the preparation and storage of solutions have been described previously (Cogswell et al, 2001).…”

Section: Methodsmentioning

confidence: 99%

“…Affinities were determined in competition experiments with the probe molecule 2-hydroxy-3,5-diiodo-N-[2(diethylamino)ethyl]benzamide (DEDIC), recently developed in our laboratory (Cogswell et al, 2001). Addition of DEDIC, an iodinated local anesthetic analog, to AGP results in quenching of the protein's native tryptophan fluorescence by binding with a known K D .…”

mentioning

confidence: 99%

“…This selectivity permits the determination of drug affinities to the F1*S variant in naturally occurring heterogeneous AGP (as is available commercially) and therefore obviates the need to first separate the variants chromatographically (Cogswell et al, 2001). The importance of determining affinities to the variants individually is underscored by observations that the major and minor variants bind to many drugs with differing affinities (Hervé et al, 1998).…”

mentioning

confidence: 99%

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Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α₁-Acid Glycoprotein

Taheri

Cogswell²,

Gent³

et al. 2003

J Pharmacol Exp Ther

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Understanding the interaction of local anesthetics (LAs) with plasma proteins is essential to understanding their systemic pharmacology and toxicology. The molecular determinants of LA binding to the major variant (F1*S) of human ␣ 1 -acid glycoprotein (AGP) were therefore investigated spectrofluorometrically using whole AGP and a novel, F1*S variant-selective probe previously developed in our laboratory. Equilibriumcompetitive displacement of this probe by LAs, observed by the recovery of AGP's fluorescence as the quenching probe was displaced from its high-affinity site, was characterized by inhibitory dissociation constants for the various LAs. The importance of electrostatic factors was assessed by examining the pH dependent binding of an ionizable LA, lidocaine, using the quaternary lidocaine derivative triethylammonium chloride] to control for pH dependent ionization of AGP. Uncharged lidocaine bound with at least 8 times the affinity of protonated lidocaine (K D ϭ 4.0 Ϯ 0.6 M and Ͼ32 M, respectively). This result is inconsistent with the current model of the AGP-binding site, which depicts a buried pocket having a negatively charged region that interacts with the amino termini of basic drugs. Consistent with the model, however, two sets of structurally homologous LAs (mepivacaine, ropivacaine, bupivacaine, and lidocaine, RAD-240, RAD-241, RAD-242, L-30, W-6603) demonstrated a strong positive correlation between hydrophobicity (measured as the octanol:buffer partition coefficient of the neutral species) and their free energies of dissociation. Given that the tertiary structure of AGP has proven refractory to resolution, these structure-activity studies should contribute to understanding the nature of the binding site on this important protein.Understanding the interaction of local anesthetics with plasma proteins is essential to predicting their systemic pharmacology and toxicology. Many basic drugs, including local anesthetics (LAs) and class I antiarrythmics, are bound in blood principally or in part by AGP (Routledge, 1986;Stanski and Watkins, 1986;Wood, 1986;Kremer et al., 1988). The binding of a drug to a plasma protein reduces its free fraction in serum, thus reducing its availability for active uptake or diffusion into surrounding tissue and significantly influencing its pharmacokinetics, toxicity, etc. (Wood, 1986).For example, the local anesthetic bupivacaine binds tightly to AGP (with K D ϭ 1 M) (Essassi et al., 1989), and this binding may mitigate the systemic toxicity of bupivacaine (Wulf et al., 1991;Mazoit et al., 1996).Indeed, altered pharmacokinetics have been observed following the binding of AGP to the LAs lidocaine and cocaine, and the same holds true with other clinically relevant amphipathic amines: amitriptyline, chlorpromazine, nicardipine, and verapamil (Benet and Hoener, 2002). For example, AGP concentration has been shown to correlate inversely with the free fraction of the LA ropivacaine 60 min after epidural injection (Porter et al., 2001). Also, one of the AGP variants...

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Section: Methodssupporting

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α₁-Acid Glycoprotein

Taheri

Cogswell²,

Gent³

et al. 2003

J Pharmacol Exp Ther

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Evaluation of a hydrazide‐linked α₁‐acid glycoprotein chiral stationary phase: Separation of R‐ and S‐propranolol

Xuan

Hage²

2006

J of Separation Science

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The binding and chiral separation of R- and S-propranolol was investigated on a new type of alpha1-acid glycoprotein (AGP) column. This column was prepared through the controlled and mild oxidation of AGP, followed by the immobilization of this protein to hydrazide-activated silica. The effects of temperature, pH, ionic strength, and organic modifiers on the retention and separation of R- and S-propranolol were investigated on this column. Both the association equilibrium constants and number of binding sites for R/S-propranolol on the AGP column were found to increase with temperature and affect the measured retention factors for these compounds. Regarding the other factors, a change in the organic modifier concentration was found to give the largest change in retention and separation. It was found through these studies that both coulombic and hydrophobic interactions played important roles in determining the retention of R- and S-propranolol on the AGP column. The efficiency and separation impedance of this system were also considered. Under the final optimum conditions identified in this study, it was possible to separate R- and S-propranolol with a resolution of greater than 1.38 in less than 5 min on a 4.1 mm I.D. x 5 cm column.

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Investigation of genetic variants of α-1 acid glycoprotein by ultra-performance liquid chromatography–mass spectrometry

et al. 2008

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Genetic variants of human plasma alpha-1 acid glycoprotein (AGP) have been studied in cancer, compared with a group of healthy control. AGP has four genetic variants: AGP F1, F2, and S variants correspond to the ORM1 gene whereas AGP A corresponds to the ORM2 gene. The proportion of ORM1 and ORM2 variants were studied in plasma using a novel UPLC-MS method. Plasma total AGP level was 0.5 +/- 0.2 g L(-1) and the proportions of the ORM1 and ORM2 variants were 76.3 +/- 8.2% and 23.7 +/- 8.2%, respectively. In cancer plasma AGP levels increased fourfold and the proportion of ORM1 variants increased to 88.7 +/- 6.8%. Changes in the proportion of genetic variants due to cancer were clearly significant, as shown by statistical analysis. Three different cancer types have been studied, lymphoma, melanoma, and ovarian cancer. The results did not show any difference depending on cancer type. The results indicate that, in accordance with prior expectations, the ORM1 variant is predominantly responsible for the acute-phase property of AGP.

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Development of a novel probe for measuring drug binding to the F1*S variant of human alpha 1‐acid glycoprotein

Cited by 14 publications

References 21 publications

Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α₁-Acid Glycoprotein

Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α₁-Acid Glycoprotein

Evaluation of a hydrazide‐linked α₁‐acid glycoprotein chiral stationary phase: Separation of R‐ and S‐propranolol

Investigation of genetic variants of α-1 acid glycoprotein by ultra-performance liquid chromatography–mass spectrometry

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Development of a novel probe for measuring drug binding to the F1*S variant of human alpha 1‐acid glycoprotein

Cited by 14 publications

References 21 publications

Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α1-Acid Glycoprotein

Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α1-Acid Glycoprotein

Evaluation of a hydrazide‐linked α1‐acid glycoprotein chiral stationary phase: Separation of R‐ and S‐propranolol

Investigation of genetic variants of α-1 acid glycoprotein by ultra-performance liquid chromatography–mass spectrometry

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Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α₁-Acid Glycoprotein

Hydrophobic and Ionic Factors in the Binding of Local Anesthetics to the Major Variant of Human α₁-Acid Glycoprotein

Evaluation of a hydrazide‐linked α₁‐acid glycoprotein chiral stationary phase: Separation of R‐ and S‐propranolol